@ASCII-only I mostly like that you don't have to import anything to get regexes work, but it's good that there are lots of good features in there, too. I just don't know what many of those features are :D

Or they think that what string manipulation functions that are already attached to the str type is usually sufficient and regex capabilities are more for the crazier substitutions. Lookbehinds and lookaheads and so on.

Challenge description
A Langford string of order N is defined as follows:
The length of the string is equal to 2*N,
The string contains first N letters of the English alphabet, each letter appearing twice,
For each pair of the same letters, there are M letters between them, where M is that let...

Definition
Two integers are coprime if they share no positive common divisors other than 1.
Example
a(11) = 6 because 6 is coprime with the last two predecessors (namely, 11 and 13) and 6 has not appeared before.
Notes
Note that the sequence is not ascending, meaning that an element can...

Blunt the images
code-golf image-processing
Introduction
Given a PNG as input, blur the image using the method described below.
Method
To get the RGB value of each pixel, use the following equation:
Where is the sum of the red values of each of the adjacent pixels squared. N is the numbe...

@βετѧΛєҫαγ I think it's clear already, but just in case the example causes confusion, it might be worth emphasising that each pixel is calculated based on the original pixels that were its neighbours, ignoring that some of these have changed

Definition
Two integers are coprime if they share no positive common divisors other than 1.
Example
a(11) = 6 because 6 is coprime with the last two predecessors (namely, 11 and 13) and 6 has not appeared before.
Notes
Note that the sequence is not ascending, meaning that an element can...

Given an integer, compute its Levenshtein code
Disclaimer: Levenshtein coding is completely unrelated to the Levenshtein edit distance metric.
<insert long story about why Levenshtein codes need to be calculated here.>
The code
Levenshtein coding is a system of assigning binary codes to nonne...

Someone needs to make a script which takes a sandbox post and automatically fills out the 'Ask a Question' feed. Then, when post has been posted, it removes the body of the sandbox post and deletes it.

Introduction
Given a PNG as input, blur the image using the method described below.
Method
To get the RGB value of each pixel, use the following equation:
Where is the sum of the red values of each of the adjacent pixels squared. N is the number of adjacent pixels (e.g. a corner pixel will...

@Dennis - F works on a list of list argument just fine (jelly.flatten is also fine) and LÆR%@€ on a list produces a list of lists - however LÆR%@€F produces the same list of lists, only adding another F actually flattens. What am I missing?

Challenge description
A Langford string of order N is defined as follows:
The length of the string is equal to 2*N,
The string contains first N letters of the English alphabet, each letter appearing twice,
For each pair of the same letters, there are M letters between them, where M is that let...

@DJMcMayhem On the one hand, given that Langford pairings are a topic in mathematics I wouldn't have been surprised if they'd come up with it themselves coincidentally, but given that they mention Reddit themselves it makes things a bit awkward

There are three reasons why I think Project Euler etc. questions shouldn't be posted here.
The first is copyright. The question submitter
... represents, warrants and agrees that it will not contribute any Subscriber Content that (a) infringes, violates or otherwise interferes with any copy...

When we've had real star problems in the past, it's been every message. This time, most of them are the type of messages that get starred anyway. I think we just happen to have had a high density of starrable messages in a short period of time

A ballot number, which we'll label B, is the number of ways of arranging the numbers from 1 through B(B+1)/2 into a triangle, such that each row and column
of the triangle is in any increasing order. The first four ballot numbers are:
a(0) = 1
a(1) = 1
a(2) = 1
a(3) = 2
a(3) is 2, which means...

Definition
Two integers are coprime if they share no positive common divisors other than 1.
Example
a(11) = 6 because 6 is coprime with the last two predecessors (namely, 11 and 13) and 6 has not appeared before.
Notes
Note that the sequence is not ascending, meaning that an element can...

@JonathanAllan @€F is a fork; tt first applies F to the argument, then calls @€ with the previous return value as left argument, and the result as right argument. LÆR%@€⁸F does what it's supposed to, explicitly specifying ⁸ (left argument) as the right argument of @€. LÆR⁸%þF is golfier.

Thorn or þorn (Þ, þ) is a letter in the Old English, Gothic, Old Norse and modern Icelandic alphabets, as well as some dialects of Middle English. It was also used in medieval Scandinavia, but was later replaced with the digraph th, except in Iceland, where it survives. The letter originated from the rune ᚦ in the Elder Fuþark and was called thorn in the Anglo-Saxon and thorn or thurs (a category of beings in Germanic paganism) in the Scandinavian rune poems. Its reconstructed Proto-Germanic name is Thurisaz.
It is pronounced as either a voiceless dental fricative [θ] or the voiced counterpart...